Interactions between photons and phonons in engineerable micro-scale and nano-scale structures and materials have attracted interest for the purpose of chip-scale radiofrequency (RF) photonic signal processing.
For example, U.S. Pat. No. 8,600,200 by P. T. Rakich et al., assigned at least in part to an assignee hereof, issued on Dec. 3, 2013 under the title “Nano-Optomechanical Transducer,” describes a nano-optomechanical transducer in which transmitting and receiving optical waveguides are mechanically coupled to a suspended membrane. An input optical signal generates an acoustic wave that propagates in the suspended membrane and modulates an optical signal propagating in the receiving waveguide. The entirety of the abovesaid U.S. Pat. No. 8,600,200 is hereby incorporated herein by reference.
In a further example, U.S. Pat. No. 9,268,092 by R. L. Jarecki, Jr. et al., which issued on Feb. 23, 2016 under the title, “Guided Wave Opto-Acoustic Device,” and which is assigned at least in part to an assignee hereof, describes a suspended membrane device in which at least one optical waveguiding member is included in the membrane. At least one phononic resonator is defined in the membrane and traversed by the optical waveguiding member. Guided-wave, stimulated Brillouin scattering (SBS) in the device can be applied in various signal-processing applications. The entirety of the abovesaid U.S. Pat. No. 9,268,092 is hereby incorporated herein by reference.
Similarly, H. Shin et al., “Tailorable stimulated Brillouin scattering in nanoscale silicon waveguides,” Nature Communications (Jun. 6, 2013) DOI: 10.1038/ncomms2943, reported on hybrid photonic-phononic waveguides that confine both photons and phonons using a Brillouin-active membrane structure, and that exhibit forward SBS gain. The entirety of the abovesaid paper by Shin et al., which is hereinafter referred to as “Shin 2013”, is hereby incorporated herein by reference.
Further, various investigators have achieved engineerable coupling between resonant photonic and phononic modes in chip-scale systems. Although resonant systems can achieve strong coupling and high frequency selectivity, they also suffer from disadvantages such as sensitivity to the optical wavelength.
However, the achievement of narrow-band RF filters that simultaneously achieve high optical power handling, low signal distortion, and optical wavelength insensitivity has been elusive. Hence there has been a need for new approaches that utilize the potentialities of photon-phonon coupling for RF signal processing with greater versatility.